F13
Siemens Loss of Voltage Sensing to Controller/AVR

Controller displays F13 Loss of Sensing; generator may run but will not regulate voltage correctly.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Open or shorted sensing wires, Blown sensing fuse, Loose terminal at alternator or controller, Failed sensing circuit on controller PCB

How to Fix / Troubleshooting

Safety first: De-energize the generator output and verify with a meter before touching any sensing or power wiring.

  • Locate sensing circuit: Identify the small-gauge wires from the alternator output that feed voltage to the Siemens controller and AVR. Refer to the wiring diagram inside the enclosure.
  • Check fuses: Inspect any inline fuses or PCB-mounted fuses in the sensing circuit. Replace blown fuses with the exact type and rating.
  • Inspect wiring and terminals: Tighten all sensing wire terminals at the alternator, AVR, and controller. Repair any damaged insulation or broken conductors.
  • Measure sensing voltage: With the generator running, carefully measure voltage at the sensing input terminals on the controller. If voltage is present but F13 persists, the controller's sensing circuit may be faulty.
  • Controller replacement: If wiring and fuses are good and sensing voltage is correct, replace the Siemens controller module following manufacturer procedures.
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Repair Difficulty

Hard 4/5

Required Part

Generator Controller PCB
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